The answer is B
Hope it helps
The labeled angle is what's called an inscribed angle. There's a theorem (fittingly called the inscribed angle theorem) that says the measure of this angle is half the measure of the circular arc that it subtends.
In this case, the angle is subtended by an arc measuring 180°. So
(4x + 6)° = 1/2 • 180°
4x + 6 = 90
4x = 84
x = 21
Let's say the tv was 100$ . Reduced by 20% means the tv is now 100 - 20 = 80% of the original price.
0.8(100) = 80$
Reduced again; by 10% means that it is now 100-10 = 90% of the 80$
0.9(80) = 72$
sale price ÷ original price
72$ / 100$ = 0.72 which is 72% of the original price. Which is a mark down of:
100 - 72 = 28%
The new price is 28% lower than the original price.